Antcin K, a Triterpenoid Compound from Antrodia camphorata, Displays Antidiabetic and Antihyperlipidemic Effects via Glucose Transporter 4 and AMP-Activated Protein Kinase Phosphorylation in Muscles

A review on the cultivation, bioactive compounds, health-promoting factors and clinical trials of medicinal mushrooms Taiwanofungus camphoratus, Inonotus obliquus and Tropicoporus linteus

Medicinal mushrooms, such as Taiwanofungus camphoratus, Inonotus obliquus, and Tropicoporus linteus, have been used in traditional medicine for therapeutic purposes and promotion of overall health in China and many East Asian countries for centuries. Modern pharmacological studies have demonstrated the large amounts of bioactive constituents (such as polysaccharides, triterpenoids, and phenolic compounds) available in these medicinal mushrooms and their potential therapeutic properties. Due to the rising demand for the health-promoting medicinal mushrooms, various cultivation methods have been explored to combat over-harvesting of the fungi. Evidence of the robust pharmacological properties, including their anticancer, hypoglycemic, hypolipidemic, antioxidant, and antiviral activities, have been provided in various studies, where the health-benefiting properties of the medicinal fungi have been further proven through numerous clinical trials. In this review, the cultivation methods, available bioactive constituents, therapeutic properties, and potential uses of T. camphoratus, I. obliquus and T. linteus are explored.

Alleviating Effects of Ovatodiolide and Antcin K Supplements on High-Fat Diet-Induced Cardiovascular Dysfunction in ApoE-Knockout Mice by Attenuating Oxidative Stress

A high-fat diet (HFD) is a major risk factor for cardiovascular diseases. Many pure compounds have been demonstrated to be effective in treating cardiovascular diseases. In this study, we investigated the alleviating effects of oral ovatodiolide and antcin K (OAK) supplements on HFD-induced cardiovascular dysfunction in apolipoprotein E (ApoE)-knockout mice. Cardiovascular dysfunction was induced in ApoE-knockout mice by feeding them an HFD for 12 weeks. The degree of cardiovascular dysfunction was assessed through echocardiography, hematological and biochemical analyses, and immunofluorescence and immunohistochemical staining. The HFD-fed mice exhibited cardiovascular dysfunction-abnormal blood biochemical index. The arterial wall tissue exhibited the marked deposition of lipids, upregulated expression of vascular cell adhesion molecule-1 and CD36 receptors, and downregulated expression of the ABCA1 receptor. Macrophages isolated from the peritoneal cavity of the mice exhibited increased levels of lipid accumulation, reactive oxygen species, and CD11b expression but reduced mitochondrial membrane potential. The expression of superoxide dismutase 2 was downregulated and that of tumor necrosis factor-α was upregulated in the myocardial tissue. Oral OAK supplements twice a day for 12 weeks significantly mitigated HFD-induced cardiovascular dysfunction in the experimental mice. Oral OAK supplements appear to be a promising strategy for treating HFD-induced cardiovascular dysfunction. The underlying mechanisms may involve the reduction of lipid accumulation in the artery and oxidative stress and inflammation in the cardiovascular tissue.

Botanical Antcin K Alleviates High-Fat Damage in Palm Acid Oil-Treated Vascular Endothelial Cells and Macrophages

Lipid metabolism disorder is the most critical risk factor for atherosclerosis, and the process involves lipid deposition in the arterial intima. In Taiwan, antcin K, an active triterpenoid from the fruiting bodies of Antrodia camphorata, has been considered a potential lipid-lowering agent. Despite this, the possible therapeutic mechanisms of antcin K remain unclear. To explore the crucial role of botanical antcin K in reducing atherosclerotic plaque, we used SVEC4-10 vascular endothelial cells and RAW264.7 macrophages with palm acid oil-induced high-fat damage as our cell models. Our results showed through using the DPPH assay that antcin K had excellent free radical scavenging ability. Antcin K treatment can significantly alleviate the high-fat damage and reduce the levels of inflammatory factors of TNF-α and IL-1β in vascular endothelial cells and macrophages, as shown through MTT assay and ELISA. Furthermore, antcin K treatment can effectively enhance migration ability and clear lipid deposition in macrophages, as shown by using cell migration assay and oil red O staining. When stained with immunofluorescence, antcin K was shown to significantly decrease the expression of adhesion molecules of vascular cell adhesion molecule 1 (VCAM-1) in vascular endothelial cells involved in monocyte migration and inflammation. Antcin K not only reduced the expression of the CD36 scavenger receptor but also augmented the expression of Kruppel-like factor 4 (KLF4) transcription factor in macrophages, which inhibits the transformation of macrophages into foam cells underlying the pathological process of atherosclerosis. Taking our findings into account, we suggested that botanical antcin K could have therapeutic potential for the treatment of atherosclerosis.

Chemical Composition and Chronic Toxicity of Disc-Cultured Antrodia cinnamomea Fruiting Bodies

Antrodia cinnamomea (AC) is a popular fungus for use as folk medicine in health maintenance and disease prevention and treatment. Disc culture is a novel technique for producing AC fruiting bodies. This study aimed to investigate the bioactive components and toxicological properties of disc-cultured AC fruiting body powders (ACP) in rats. The HPLC technique was used to quantify the composition of bioactive triterpenoids in ACP. Toxicological properties were evaluated on male and female Sprague-Dawley rats receiving ACP orally at 200, 600, and 1000 mg/kg body weight for 90 days; the control group received only distilled water. The results show that ACP contained seven important AC index compounds, namely antcins A, B, C, K, and H, dehydrosulphurenic acid, and dehydroeburicoic acid. At the tested doses, oral ACP administration for 90 days caused no mortality, adverse effects on general health, body and organ weights, and food intake. Furthermore, no significant variations were observed in hematological and biochemical parameters among either sex of ACP-treated and control animals. An histopathological examination of vital organs showed no significant structural changes in organs, even in high-dose ACP-treated animals. This study indicated that ACP contained the major bioactive triterpenoids of AC fruiting bodies, and its no-observed-adverse-effect level (NOAEL) was 1000 mg/kg/day, about 20 times the recommended daily intake.

Nano Modification of Antrodia Cinnamomea Exhibits Anti-Inflammatory Action and Improves the Migratory Potential of Myogenic Progenitors

The skeletal muscle progenitors’ proliferation and migration are crucial stages of myogenesis. Identifying drug candidates that contribute to myogenesis can have a positive impact on atrophying muscle. The purpose of the study is to synthesize the Antrodia cinnamomea (AC)-β-cyclodextrin (BCD) inclusion complex (IC) and understand its in vitro pro-regenerative influence in murine skeletal C2C12 myoblasts. The IC was subjected to various nano-characterization studies. Fluorescent IC was synthesized to understand the cellular uptake of IC. Furthermore, 25 µg/mL, 12.5 µg/mL, and 6.25 µg/mL of IC were tested on murine C2C12 skeletal muscle cells for their anti-inflammatory, pro-migratory, and pro-proliferative action. The cellular internalization of IC occurred rapidly via pinocytosis. IC (252.6 ± 3.2 nm size and −37.24 ± 1.55 surface charge) exhibited anti-inflammatory action by suppressing the secretion of interleukin-6 and enhanced cell proliferation with promising cytocompatibility. A 12.5 μg/mL dose of IC promoted cell migration in 24 h, but the same dose of AC significantly reduced cell migration, suggesting modification by BCD. Molecular studies revealed that IC promoted C2C12 myoblasts migration by upregulating long non-coding RNA (lncRNA) NEAT-1, SYISL, and activating the pPKC/β-catenin pathway. Our study is the first report on the pro-proliferative and pro-migratory effects of BCD-modified extracts of AC.

Ameliorated effects of a lipopeptide surfactin on insulin resistance in vitro and in vivo

Surfactin, produced by Bacillus amyloliquefaciens fmb50, was used to treat insulin‐resistant (IR) hepatocyte. It was found that surfactin increased glucose consumption in insulin‐resistant HepG2 (IR‐HepG2) cells and ameliorated IR by increasing glucose transporter 4 (GLUT4) protein expression and AMP‐activated protein kinase (AMPK) mRNA expression, promoting GLUT4 translocation and activating phosphatidylinositol 3‐kinase (PI3K)/protein kinase B (Akt) in IR‐HepG2 cells. Meanwhile, surfactin downregulated protein expression of phosphoenolpyruvate carboxy kinase (PEPCK) and glucose‐6‐phosphatase (G6Pase), further inhibiting hepatic gluconeogenesis. In addition, surfactin played important roles in eliminating reactive oxygen species (ROS), improving mitochondrial dysfunction, and inhibiting proinflammatory mediators. We observed that surfactin promoted glucose consumption, meanwhile increased translocation and protein expression of GLUT4 in Caco‐2 cells. These results confirmed the conclusion in hepatic cells. Furthermore, surfactin supplement decreased body weight, food intake, and fasting blood glucose of type 2 diabetes mellitus (T2DM) mice induced by streptozotocin (STZ)/high‐fat diet (HFD). Our data indicated that surfactin ameliorated insulin resistance and lowered blood glucose in intro and in vivo.

A network pharmacology-based strategy to explore the pharmacological mechanisms of Antrodia camphorata and antcin K for treating type II diabetes mellitus

BACKGROUND

Diabetes mellitus is a chronic carbohydrate metabolism disorder, which could develop a series of complications and thus lead to poor quality of life or even mortality. Antrodia camphorata is a rare parasitic fungus and has been proven to be effective for treating type II diabetes.

PURPOSE

This study aims to evaluate the anti-diabetic activities of A. camphorata and its main compound antcin K, as well as to demonstrate the mechanisms.

STUDY DESIGN AND METHODS

Network pharmacology was used to explore the potential targets of 12 major compounds of A. camphorata on diabetes. The core targets were analyzed by protein-protein interactions and the key pathways were enriched by Kyoto Encyclopedia of Genes and Genomes (KEGG). The anti-diabetic effects of A. camphorata and antcin K were evaluated using a high-fat diet (HFD)-induced diabetic mice model and oral glucose tolerance test (OGTT). The mRNA expressions were assessed using qPCR.

RESULTS

Network pharmacology revealed 17 core targets between the 12 compounds and diabetes. The insulin resistance and NF-κB signaling pathways were enriched using KEGG. Five insulin resistance-related targets were focused on and antcin K (1/2) was discovered in the compound-target-pathway network. In vivo studies exhibited that A. camphorata and antcin K could dose-dependently reduce blood levels of glucose and lipids, decrease serum levels of insulin and leptin, and increase serum levels of adiponectin in HFD mice (p < 0.05). The mechanism could be through modulating the expressions of Tnfα, Il6, and Pparγ. The OGTT test also showed the down-regulatory effects of A. camphorata and antcin K on blood glucose.

CONCLUSION

This study demonstrates that A. camphorata and its major compound antcin K possess potent anti-diabetic effects. The mechanism may be through the insulin resistance pathway.

C2C12 cell model: its role in understanding of insulin resistance at the molecular level and pharmaceutical development at the preclinical stage

OBJECTIVES

The myoblast cell line, C2C12, has been utilised extensively in vitro as an examination model in understanding metabolic disease progression. Although it is indispensable in both preclinical and pharmaceutical research, a comprehensive review of its use in the investigation of insulin resistance progression and pharmaceutical development is not available.

KEY FINDINGS

C2C12 is a well-documented model, which can facilitate our understanding in glucose metabolism, insulin signalling mechanism, insulin resistance, oxidative stress, reactive oxygen species and glucose transporters at cellular and molecular levels. With the aid of the C2C12 model, recent studies revealed that insulin resistance has close relationship with various metabolic diseases in terms of disease progression, pathogenesis and therapeutic management. A holistic, safe and effective disease management is highly of interest. Therefore, significant efforts have been paid to explore novel drug compounds and natural herbs that can elicit therapeutic effects in the targeted sites at both cellular (e.g. mitochondria, glucose transporter) and molecular level (e.g. genes, signalling pathway).

SUMMARY

The use of C2C12 myoblast cell line is meaningful in pharmaceutical and biomedical research due to their expression of GLUT-4 and other features that are representative to human skeletal muscle cells. With the use of the C2C12 cell model, the impact of drug delivery systems (nanoparticles and quantum dots) on skeletal muscle, as well as the relationship between exercise, pancreatic β-cells and endothelial cells, was discovered.

Terpenoids from the medicinal mushroom Antrodia camphorata: chemistry and medicinal potential

Covering: up to February 2020Antrodia camphorata is a medicinal mushroom endemic to Taiwan for the treatment of intoxication, liver injury, cancer, and inflammation. Owing to its rare occurrence and potent pharmacological activities, efforts have been devoted to identify its bioactive constituents, especially terpenoids. Since 1995, a total of 162 terpenoids including triterpenoids, meroterpenoids, sesquiterpenoids, diterpenoids, and steroids have been characterized. The ergostane-type triterpenoids (antcins) and meroterpenoids (antroquinonols) are characteristic constituents of A. camphorata. The terpenoids show anti-cancer, hepatoprotective, anti-inflammatory, anti-diabetic, and neuroprotective activities. This review summarizes the research progress on terpenoids in A. camphorata during 1995-2020, including structural diversity, resources, biosynthesis, pharmacological activities, metabolism, and toxicity. The medicinal potential of the terpenoids is also discussed.

Serjanic Acid Improves Immunometabolic Markers in a Diet-Induced Obesity Mouse Model

Plant extracts from Cecropia genus have been used by Latin-American traditional medicine to treat metabolic disorders and diabetes. Previous reports have shown that roots of Cecropia telenitida that contains serjanic acid as one of the most prominent and representative pentacyclic triterpenes. The study aimed to isolate serjanic acid and evaluate its effect in a prediabetic murine model by oral administration. A semi-pilot scale extraction was established and serjanic acid purification was followed using direct MALDI-TOF analysis. A diet induced obesity mouse model was used to determine the impact of serjanic acid over selected immunometabolic markers. Mice treated with serjanic acid showed decreased levels of cholesterol and triacylglycerols, increased blood insulin levels, decreased fasting blood glucose and improved glucose tolerance, and insulin sensitivity. At transcriptional level, the reduction of inflammation markers related to adipocyte differentiation is reported.

Antidiabetic and Antihyperlipidemic Effects of Sulphurenic Acid, a Triterpenoid Compound from Antrodia camphorata, in Streptozotocin-Induced Diabetic Mice

The present study was designed to evaluate the protective effect of sulphurenic acid (SA), a pure compound from Antrodia camphorata, on diabetes and hyperlipidemia in an animal model study and to clarify the underlying molecular mechanism. Diabetes was induced by daily 55 mg/kg intraperitoneal injections of streptozotocin (STZ) solution over five days. Diabetic mice were randomly divided into six groups and orally gavaged with SA (at three dosages) or glibenclamide (Glib), fenofibrate (Feno) or vehicle for 3 weeks. Our findings showed that STZ-induced diabetic mice had significantly increased fasting blood glucose, glycated hemoglobin (HbA1C), plasma triglyceride (TG), and total cholesterol (TC) levels (p < 0.001, p < 0.001, p < 0.001, and p < 0.05, respectively) but decreased blood insulin, adiponectin, and leptin levels compared to those of the control group (p < 0.001, p < 0.001, and p < 0.001, respectively). Administration of SA to STZ-induced diabetic mice may lower blood glucose but it increased the insulin levels with restoration of the size of the islets of Langerhans cells, implying that SA protected against STZ-induced diabetic states within the pancreas. At the molecular level, SA treatment exerts an increase in skeletal muscle expression levels of membrane glucose transporter 4 (GLUT4) and phospho-Akt to increase the membrane glucose uptake, but the mRNA levels of PEPCK and G6Pase are decreased to inhibit hepatic glucose production, thus leading to its hypoglycemic effect. Moreover, SA may cause hypolipidemic effects not only by enhancing hepatic expression levels of peroxisome proliferator-activated receptor α (PPARα) with increased fatty acid oxidation but also by reducing lipogenic fatty acid synthase (FAS) as well as reducing mRNA levels of sterol regulatory element binding protein (SREBP)1C and SREBP2 to lower blood TG and TC levels. Our findings demonstrated that SA displayed a protective effect against type 1 diabetes and a hyperlipidemic state in STZ-induced diabetic mice.

Antrodia Cinnamomea Prolongs Survival in a Patient with Small Cell Lung Cancer

Introduction: Antrodia cinnamomea (AC) is an extremely rare medicinal fungus native to forested regions of Taiwan. It possesses numerous biological activities, especially anti-tumor effects shown in various in vitro cancer cells and in vivo animal models. However, there are few clinical reports about AC as a treatment for cancer patients. This report attempts to demonstrate the therapeutic effect of dish-cultured AC (DAC) on a small cell lung cancer (SCLC) patient taken orally for an extended duration. Patient concerns: An 88-year-old male with a history of diabetes mellitus and hypertension visited the outpatient department with the symptoms of dyspnea and a cough for two weeks. After a diagnosis of SCLC, the patient declined both chemotherapy and radiotherapy because of the side effects and only accepted supportive care without additional therapy. Diagnosis: Limited-stage SCLC (T4N2M1a, stage IV) after the chest radiograph, computed tomography-guided biopsy, and pathological diagnosis. Interventions: The patient was prescribed DAC with an increasing dosage, from 5 g/d up to 10 g/d DAC, for six months, without radiation or chemotherapy treatment. Outcomes: DAC caused the tumor to shrink substantially. Surprisingly, the patient survived for 32 months without relapse after six months of DAC treatment. Laboratory examinations indicated that the patient's health had improved significantly, reverting to near normal levels. Notably, he had a good quality of life with a high Barthel index score. Unfortunately, this patient died of septic shock caused by acute cholangitis. Conclusion: DAC may exert an anti-cancer effect, which can lead to tumor regression. This is supposed to be achieved by the combined DAC's immunomodulatory, anti-angiogenic, anti-metastatic, anti-proliferative, and pro-apoptotic effects mediated through multiple signaling pathways. We propose that DAC can be used as a complementary medicine to prolong the life expectancy and improve the life quality of SCLC patients.

Antcins, triterpenoids from Antrodia cinnamomea, as new agonists for peroxisome proliferator-activated receptor α

Peroxisome proliferator-activated receptor α (PPARα) is a nuclear hormone receptor that transcriptionally regulates lipid metabolism and inflammation; therefore, PPARα agonists are promising agents to treat dyslipidemia and metabolic disorders. PPARα full agonists, such as fibrates, are effective anti-hypertriglyceride agents, but their use is limited by adverse side effects. Hence, the aim of this study was to identify small molecules that can activate PPARα while minimizing the adverse effects. Antrodia cinnamomea, a rare medical mushroom, has been used widely in Asian countries for the treatment of various diseases, including liver diseases. Antcin B, H and K (antcins) and ergostatrien-3β-ol (EK100) are bioactive compounds isolated from A. cinnamomea with anti-inflammatory actions. Antcins, ergostane-type triterpenoids, contain the polar head with carboxylate group and the sterol-based body. Here, we showed at the first time that sterol-based compounds, antcins, but not EK100, activate PPARα in a cell-based transactivation study. The in silico docking studies presented several significant molecular interactions of antcins, including Tyr314, and His440 in the ligand-binding domain of PPARα, and these interactions are required for helix 12 (H12) stabilization. We propose that PPARα activation activity of antcins is related to their binding mode which requires conventional H12 stabilization, and that antcins can be developed as safe selective PPARα modulators.

Isolation and Identification of Potent Antidiabetic Compounds from Antrodia cinnamomea-An Edible Taiwanese Mushroom

Antrodia cinnamomea (AC), an edible Taiwanese mushroom, has been recognized as a valuable natural resource with vast biological and medicinal benefits. Recently, the hypoglycemic and anti-diabetic effects of AC were mentioned in several studies. However, no studies have investigated α-glucosidase inhibitors from AC fruiting bodies (ACFB) as they relate to type 2 diabetes (T2D) treatment. The purpose of this study was to gain evidence of potent α-glucosidase inhibitory effects, as well as isolate, identify and characterize the active compounds of ACFB. The MeOH extract of ACFB demonstrated potent α-glucosidase inhibitory activity, and possessed high pH stability (pH 2⁻11) and thermostable properties at 40⁻50 °C. Further purification led to the isolation of eight constituents from ACFB, identified as: 25S-antcin K (1), 25R-antcin K (2), dehydrosulphurenic acid (3), 25S-antcin I (4), 25S-antcin B (5), 25R-antcin B (6), dehydroeburicoic acid (7) and eburicoic acid (8). Notably, the ACFB extract and its identified compounds, except 1, 4, and 6 demonstrated a greater effect (EC50 = 0.025⁻0.21 mg/mL) than acarbose (EC50 = 0.278 mg/mL). As such, these active compounds were determined to be new potent mushroom α-glucosidase inhibitors. These active compounds were also identified on the HPLC fingerprints of ACFB.

Amelioration effects of nanoencapsulated triterpenoids from petri dish-cultured Antrodia cinnamomea on reproductive function of diabetic male rats

PURPOSE

Nanoencapsulated triterpenoids from petri dish-cultured Antrodia cinnamomea (PAC) and its amelioration effects on reproductive function in diabetic rats were investigated.

MATERIALS AND METHODS

PAC encapsulated in silica-chitosan nanoparticles (Nano-PAC) was prepared by the biosilicification method. The diabetic condition in male Sprague Dawley rats was induced by high-fat diet and streptozotocin (STZ). Three different doses of Nano-PAC (4, 8, and 20 mg/kg) were administered for 6 weeks. Metformin and control of nanoparticles (Nano-con) were taken as positive and negative controls, respectively.

RESULTS

The average particle size was ~79.46±1.63 nm, and encapsulation efficiency was ~73.35%±0.09%. Nano-PAC administration improved hyperglycemia and insulin resistance. In addition, Nano-PAC ameliorated the morphology of testicular seminiferous tubules, sperm morphology, motility, ROS production, and mitochondrial membrane potential. Superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) antioxidant, as well as testosterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH) were increased, whereas proinflammatory cytokines TNF-α, IL-6, and IFN-γ were decreased.

CONCLUSION

In the present study, we successfully nanoencapsulated PAC and found that a very low dosage of Nano-PAC exhibited amelioration effects on the reproductive function of diabetic rats.

Sequential Biotransformation of Antcin K by Bacillus subtilis ATCC 6633

The biotransformation of antcin K, a major ergostane triterpenoid from the fruiting bodies of Antrodia cinnamomea, by Bacillus subtilis (B. subtilis) ATCC 6633 was studied. Four metabolites from the biotransformation were isolated with preparative high-performance liquid chromatography and identified as 25S-antcin K 26-O-β-glucoside, 25R-antcin K 26-O-β-glucoside, 25S-antcin K 26-O-β-(6′-O-succinyl)-glucoside, and 25R-antcin K 26-O-β-(6′-O-succinyl)-glucoside with mass and nuclear magnetic resonance spectral analysis. By using either 25S-antcin K 26-O-β-glucoside or 25R-antcin K 26-O-β-glucoside as the biotransformation precursor, it was proven that 25S-antcin K 26-O-β-(6′-O-succinyl)-glucoside and 25R-antcin K 26-O-β-(6′-O-succinyl)-glucoside were biotransformed from 25S-antcin K 26-O-β-glucoside and 25R-antcin K 26-O-β-glucoside, respectively. To the best of our knowledge, this is the first study on the glycosylation of triterpenoids from A. cinnamomea, and the first time the succinylation of triterpenoid glycosides by microorganisms has been found. In addition, all four antcin K glucoside derivatives are new compounds.

Improving insulin resistance with Antrodia cinnamomea mycelium powder to induce a hypoglycemic effect in dexamethasone‑induced insulin‑resistant rats

Insulin resistance is a major factor in type II diabetes development, occurring when insulin levels are normal, but do not have normal interactions with adipose, muscle or liver tissue. The present study aimed to explore the hypoglycemic effect of Antrodia cinnamomea (AC) mycelium powder by evaluating its impact on insulin resistance and plasma free fatty acid (FFA) levels in steroid‑induced insulin‑resistant (SIIR) rats. Male Wistar rats were administered dexamethasone for 5 days to induce insulin resistance. The SIIR rats were subsequently randomly assigned into three experimental groups (EGs) and a control group (CG), where saline was orally administered. The EGs were orally administered different doses of AC (100, 200 or 500 mg/kg) and an optimal dose for further study was determined. Changes in plasma insulin and glucose levels were calculated to investigate the hypoglycemic effect of AC. To evaluate insulin resistance, the homeostasis model assessment‑estimated insulin resistance of the SIIR rats was determined. Changes in plasma FFA levels were detected and levels of insulin signal proteins (IRS‑1, GLUT‑4 and PI3K) were analyzed by western blot to elucidate AC's mechanism of action. The SIIR rats exhibited significantly decreased plasma glucose levels in the first 30 min, with plasma FFA levels displaying a marked downward trend (P<0.05) when they were administered the optimal dose of AC (200 mg/kg). The decrease in plasma glucose and FFA levels was significantly larger in the EG compared to the CG, and insulin signal protein levels were also significantly increased (P<0.05). The hypoglycemic effect observed may be due to decreased plasma FFA levels and increased expression of intracellular insulin signal proteins. Furthermore, insulin sensitivity was enhanced, indicating that AC acts as an insulin sensitizer in insulin resistant animal models.

Eburicoic Acid, a Triterpenoid Compound from Antrodia camphorata, Displays Antidiabetic and Antihyperlipidemic Effects in Palmitate-Treated C2C12 Myotubes and in High-Fat Diet-Fed Mice

This study was designed to investigate the antidiabetic and antihyperlipidemic effects and mechanisms of eburicoic acid (TRR); one component of Antrodia camphorata in vitro and in an animal model for 14 weeks. Expression levels of membrane glucose transporter type 4 (GLUT4); phospho-5′-adenosine monophosphate-activated protein kinase (AMPK)/total AMPK; and phospho-Akt/total Akt in insulin-resistant C2C12 myotube cells were significantly decreased by palmitate; and such decrease was prevented and restored by TRR at different concentrations. A group of control (CON) was on low-fat diet over a period of 14 weeks. Diabetic mice; after high-fat-diet (HFD) induction for 10 weeks; were randomly divided into six groups and were given once a day oral gavage doses of either TRR (at three dosage levels); fenofibrate (Feno) (at 0.25 g/kg body weight); metformin (Metf) (at 0.3 g/kg body weight); or vehicle (distilled water) (HF group) over a period of 4 weeks and still on HFD. Levels of glucose; triglyceride; free fatty acid (FFA); insulin; and leptin in blood were increased in 14-week HFD-fed mice as compared to the CON group; and the increases were prevented by TRR, Feno, or Metf as compared to the HF group. Moreover, HFD-induction displayed a decrease in circulating adiponectin levels, and the decrease was prevented by TRR, Feno, or Metf treatment. The overall effect of TRR is to decrease glucose and triglyceride levels and improved peripheral insulin sensitivity. Eburicoic acid, Feno, and Metf displayed both enhanced expression levels of phospho-AMPK and membrane expression levels of GLUT4 in the skeletal muscle of HFD-fed mice to facilitate glucose uptake with consequent enhanced hepatic expression levels of phospho-AMPK in the liver and phosphorylation of the transcription factor forkhead box protein O1 (FOXO1) but decreased messenger RNA (mRNA) of phosphenolpyruvate carboxykinase (PEPCK) to inhibit hepatic glucose production; resulting in lowered blood glucose levels. Moreover; TRR treatment increased hepatic expression levels of the peroxisome proliferator-activated receptor α (PPARα) to enhance fatty acid oxidation; but displayed a reduction in expressions of hepatic fatty acid synthase (FAS) but an increase in fatty acid oxidation PPARα coincident with a decrease in hepatic mRNA levels of sterol response element binding protein-1c (SREBP-1c); resulting in a decrease in blood triglycerides and amelioration of hepatic ballooning degeneration. Eburicoic acid-treated mice reduced adipose expression levels of lipogenic FAS and peroxisome proliferator-activated receptor γ (PPARγ) and led to decreased adipose lipid accumulation. The present findings demonstrated that TRR exhibits a beneficial therapeutic potential in the treatment of type 2 diabetes and hyperlipidemia.